From: Dave Young <dyoung@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Baoquan He <bhe@redhat.com>, Xunlei Pang <xlpang@redhat.com>,
Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>,
Petr Tesarik <ptesarik@suse.cz>,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
kexec@lists.infradead.org, holzheu@linux.vnet.ibm.com,
mahesh@linux.vnet.ibm.com, hbathini@linux.vnet.ibm.com
Subject: Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section
Date: Wed, 22 Mar 2017 12:30:04 +0800 [thread overview]
Message-ID: <20170322043004.GB4424@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <87pohaxam1.fsf@xmission.com>
On 03/21/17 at 10:18pm, Eric W. Biederman wrote:
> Dave Young <dyoung@redhat.com> writes:
>
> > On 03/20/17 at 10:33pm, Eric W. Biederman wrote:
> >> Xunlei Pang <xlpang@redhat.com> writes:
> >>
> >> > As Eric said,
> >> > "what we need to do is move the variable vmcoreinfo_note out
> >> > of the kernel's .bss section. And modify the code to regenerate
> >> > and keep this information in something like the control page.
> >> >
> >> > Definitely something like this needs a page all to itself, and ideally
> >> > far away from any other kernel data structures. I clearly was not
> >> > watching closely the data someone decided to keep this silly thing
> >> > in the kernel's .bss section."
> >> >
> >> > This patch allocates extra pages for these vmcoreinfo_XXX variables,
> >> > one advantage is that it enhances some safety of vmcoreinfo, because
> >> > vmcoreinfo now is kept far away from other kernel data structures.
> >>
> >> Can you preceed this patch with a patch that removes CRASHTIME from
> >> vmcoreinfo? If someone actually cares we can add a separate note that holds
> >> a 64bit crashtime in the per cpu notes.
> >
> > I think makedumpfile is using it, but I also vote to remove the
> > CRASHTIME. It is better not to do this while crashing and a makedumpfile
> > userspace patch is needed to drop the use of it.
> >
> >>
> >> As we are looking at reliability concerns removing CRASHTIME should make
> >> everything in vmcoreinfo a boot time constant. Which should simplify
> >> everything considerably.
> >
> > It is a nice improvement..
>
> We also need to take a close look at what s390 is doing with vmcoreinfo.
> As apparently it is reading it in a different kind of crashdump process.
Yes, need careful review from s390 and maybe ppc64 especially about
patch 2/3, better to have comments from IBM about s390 dump tool and ppc
fadump. Added more cc.
Thanks
Dave
next prev parent reply other threads:[~2017-03-22 4:30 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-20 5:50 [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section Xunlei Pang
2017-03-20 5:50 ` [PATCH v3 2/3] powerpc/fadump: Use the correct VMCOREINFO_NOTE_SIZE for phdr Xunlei Pang
2017-03-20 5:50 ` [PATCH v3 3/3] kdump: Relocate vmcoreinfo to the crash memory range Xunlei Pang
2017-03-21 3:33 ` [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section Eric W. Biederman
2017-03-22 2:55 ` Dave Young
2017-03-22 3:18 ` Eric W. Biederman
2017-03-22 4:30 ` Dave Young [this message]
2017-03-22 9:34 ` Xunlei Pang
2017-03-22 12:15 ` Hari Bathini
2017-03-22 11:46 ` Hari Bathini
2017-03-22 20:48 ` Michael Holzheu
2017-03-23 9:23 ` Xunlei Pang
2017-03-23 17:46 ` Michael Holzheu
2017-03-24 11:03 ` Xunlei Pang
2017-03-22 8:55 ` Xunlei Pang
2017-03-22 9:16 ` Xunlei Pang
2017-03-22 9:17 ` Xunlei Pang
2017-03-21 9:27 ` Petr Tesarik
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